In 1977 Andreas Gruntzig performed the first successful balloon angioplasty on an obstructed human artery, thereby opening the vessel and allowing improved flow of blood.
Balloon angioplasty is a catheter-based procedure in which a long, thin tube with a deflated balloon at the tip is inserted into an artery. The balloon is guided to a stenotic lesion using X-ray fluoroscopy, rapidly inflated to a pressure of several atmospheres and deflated. Several rounds of inflation and deflation cause the stenotic lesion to crack and squash radially outward, thereby opening the obstructed lumen.
Balloon Angioplasty may be indicated for improving circulation to virtually any stenosed organ vasculature or peripheral vasculature, including opening occluded vessels during an acute heart attack; and in place of surgical endarterectomy, treatment of carotid artery stenosis, in high-risk surgical patients.
A problem associated with balloon angioplasty is that the stenotic lesion may release debris that travels to vital organs, for example the brain and/or lungs, causing vascular blockage, tissue necrosis and/or patient death.
To prevent such draconian sequela, a number of in vivo debris filter devices have been developed that are designed to capture debris released from stenotic lesions during an angioplasty procedure.
Using a guide passage, such a debris filter is positioned downstream of the intended angioplasty site and expanded to press against the tissue surrounding the lumen, thereby effectively filtering all blood passing through the lumen. A balloon angioplasty catheter is then introduced into the artery and the balloon is positioned adjacent the stenotic lesion. The balloon is inflated, the lesion releases debris and the filter captures the debris. After deflation and removal of the balloon, the filter is contracted and removed with the captured debris.
The use of in vivo debris filters during balloon angioplasty, however, may fail to prevent vascular blockage, tissue necrosis and/or patient death. To be effective, in vivo debris filters are positioned quite a distance downstream from the lesion undergoing angioplasty; considerably raising the chances that a vessel branching off the treated vessel will be located between the angioplasty balloon and the filter. Debris generated by the angioplasty will likely find its way into the branch vessel and travel to the lungs or brain, causing the above-noted sequela.
Additionally the filter itself may pose a health hazard to the patient. The deployment zone for the filter often comprises healthy vascular tissue. Positional adjustments and expansion of the filter against the healthy vascular tissue can cause tissue scars and plaques that, of themselves, provide a breeding ground for additional, full-blown, stenotic lesions.
In spite of the above-noted risk and health hazard, use of a debris filter is indicated for patients having “rupture-prone” lesions; stenotic lesions characterized by thin fibrous caps and large lipid cores. Even though it is impossible to introduce a filter once the balloon angioplasty has begun, in theory, pre-operative identification of a rupture-prone stenotic lesion would allow the patient and surgeon to weigh the risks and benefits of using an in vivo debris filter in addition to the angioplasty balloon catheter.
Unfortunately, the above theoretical solution is almost totally unworkable in practice because the very lesions that are rupture-prone are often not visible by x-ray angiography.
(Z. A. Fayad et al: “Clinical Imaging of the High-Risk or Vulnerable Atherosclerotic Plaque”; Circulation Research. 2001; 89: 305.)
The surgeon and patient, therefore, are left to grope in the dark for answers as to whether to risk patient health and deploy a debris filter.
In general, existing devices and technology present a number of additional disadvantages associated with the stand-alone in vivo debris filter, including:                1) the additional thousands of dollars to pay for each disposable filter for each surgery;        2) the difficulty in surgically deploying the filter in addition to a balloon angioplasty; and        3) the additional surgical fee charged by the surgeon for performing a second surgical procedure associated with the filter.        